Characteristic Test And Crop Yield Simulation Of Compound Soil Improved By Soft Rock To Sandy Soil

With the rapid development of society and the increasing contradiction between human and land,the protection of cultivated land is imminent.The protection and development of all available land has become a hot and difficult point in current research.The ecological environment of Mu Us Desert is fragile,and the soft rock which is easy to be eroded is distributed.At the same time,Mu Us Desert is rich in water and heat resources and has great development potential.Previous studies have shown that soft rock and sandy soil can be compounded into soil,which has been popularized and demonstrated in Mu Us Desert.However,the internal mechanism of compounded soil,the long-term stability of compounded soil structure,the water conservation under different time and space conditions,and the stability of crop yield in different years are still unknown.Therefore,based on the previous research basis,through indoor experiment,plot experiment,field experiment and model simulation,this study deeply studied the microstructure,mineral composition,particle composition,colloidal properties,mechanical properties and macro characteristics of the composite soil after the mixture of soft rock and sandy soil in different proportions(1:1,1:2,1:5),and explored the composite soil of soft rock and sandy soil The internal mechanism and structural stability of the model are discussed.The water infiltration process and water effect of soft rock and sandy soily soil were discussed.The influence of the compound soil in different climatic regions on crop yield was explored.At the same time,the change of corn yield in 26 years was simulated by rzwqm2 model.The following lists the major results from the research:(1)The microstructure and material composition of sandy soil soil were optimized after the combination of arsenite and sandy soil soil.According to the laboratory experiments,the surface of the micro particles of arsenolite was irregular,the content of secondary minerals was 22.7%,and the particle size distribution range was 0.317-709.0 ?m,mainly concentrated in the finer clayey silt section,the content of silt was 75.31%,while the micro particles of sandy soil were round,the secondary minerals were only 6.5%,and the particle size distribution range was 0.564-2000.0?m,mainly concentrated in the coarser sand section,the content of sand was 95.37%The microstructure,mineral composition and particle composition of the composite soil of 1:1 and 1:2 had been improved.In addition,the main colloid in arsenite was clay.It was found that the retention of clay in sandy soil was relatively stable,and it had relatively stable soil mechanical properties after the combination of arsenite and sandy soil(2)The structure of the composite soil was stable and the quality was improved year by year.Through the plot planting experiment,it was found that the mixture of soft rock and sandy soil soil significantly improved the sandy soil of sandy soil soil With the increased of crop planting years,the texture gradually changed from sand loam(1:2,1:5)-sandy loam(1:1)-silty soil(1:1);the bulk density of sandy soil was reduced,and the bulk density was 1:1<1:2<1:5<0:1,the soil aggregate(WR 0.25)was improved 1:1,1:2 and 1:5 increased by 29.26%,31.47%and 11.56%on average compared with WR 0.25 in sandy land,under different years,WR 0.25 in 1:2 was relatively high and most stable,the organic carbon content of each proportion of composite soil increased with the increased of planting years.Six years after planting,the average content of organic carbon in 1:1,1:2 and 1:5 tillage layers was 1.64±0.15 g/kg,1.51±0.13 g/kg and 1.77±0.082 g/kg,respectively,which was much higher than that in sandy land.At the same time,with the increase of planting years,the functional structure of composite soil was more stable,the texture composition was better,and the correlation between clay particles,aggregates and organic carbon was gradually improved.(3)The combination of soft rock and sandy soil improved the water retention performance of sandy soil significantly.Through the water infiltration experiment,it was found that the average infiltration rate of soft rock and sandy soil was 0.13 cm/min and 2.86 cm/min respectively,with the addition of soft rock,the average infiltration rate decreased gradually,the time of penetration of different mixed soil wet front into 30 cm soil column was 1:0>5:1>2:1>1:1>1:2>1:5>0:1,which showed that soft rock can effectively solve the problem of excessive seepage of sandy soil,increased the retention time of water and improved the water holding capacity of sandy soil.The model fitting of infiltration process showed that Kostiakov The accuracy of model fitting was higher.It was found that with the increase of the composite ratio,the permeability of soft sandstone and sandy soil decreased,KS decreased from 7.10 mm/min to 0.07 mm/min,soil water leakage decreased,and capillary pores and KS showed an exponential negative correlation.The results showed that in the depth direction,the water content of the surface soil(0-30cm)was higher than that of the deep soil(30-120cm)in different years,and in the time direction,the water content of the soil was higher between July and September in different years.The average water storage of composite soil in each year is 1:1>1:2>1:5.(4)When the ratio of soft rock to sandy soil was 1:2,the yield of maize was higher.The field tests were carried out in Guanzhong area(plot test)and Shanbei desert area(field test).It was found that under the plot test,when the ratio of soft rock to sandy soil was 1:2,the growth of corn plant was the best.The average yield of corn in plot test and field test was 1:2>1:1>1:5.The yield of plot test and field test were 12984,12040,11301 kg/ha,9618,8324,8105 kg/ha,respectively.The yield of corn in plot test was significantly higher than that in field test,and the yield of corn was increasing year by year.(5)Rzwqm2 model simulated the corn yield of different proportion of compound soil,and confirmed the high and stable yield of corn planted in compound soil.Through the rzwqm2 model,the corn yield of the mixed soil with different proportion was simulated under the condition of rain fed for 26 years and full irrigation.Under rain fed condition,the average yield of corn is 1:2>1:1>1:5,which was significantly related to the total rainfall and relative humidity in June,July and the growth period,but not to the minimum,maximum temperature and solar radiation;under full irrigation condition,the yield of corn in different proportion of composite soil was close,which was significantly higher than that of rain fed,and the yield of corn was significantly related to the average daily minimum temperature.According to the output value of fully irrigated yield and rain fed yield,the difference of corn yield under the ratio of 1:2 was the smallest,and the corn yield was high and stable.